This invention relates to a semiconductor device using a fluorine-added carbon film as an inter-layer insulating film, and to a manufacturing method thereof.
In order to implement enhanced integration in semiconductor devices, various approaches have been developed, including miniaturizing patterns and stacking circuits in multiple layers, and one of such approaches is a technique of configuring wirings in multiple layers. To make a multi-layered wiring structure, it is necessary to connect an n-th wiring layer and an (n+1)th wiring layer with a conductive layer while making a thin film, called inter-layer insulating film, in the remainder area other than the conductive layer.
One of typical inter-layer insulating films is a silicon oxide (SiO2) film. Recently, inter-layer insulating films are required to be low in specific inductive capacity for increasing operation speeds of devices, and various researches are being made about materials of inter-layer insulating films. Specific inductive capacity of SiO2 films is about 4, and efforts are being made toward excavation of materials having lower specific inductive capacities. As one of such efforts, SiOF film having a specific inductive capacity of 3.5 is under development toward realization. The inventor, however, is remarking fluorine-added carbon film (hereinafter called xe2x80x9cCF filmxe2x80x9d) having a still lower specific inductive capacity.
CF film is made by using a plasma apparatus that generates plasma by electron cyclotron resonance, for example, using argon gas, for example, as plasma gas, and using a gas containing compound gas of carbon and fluorine and hydrocarbon gas as the deposition gas, and exciting the deposition gas into plasma.
In actual semiconductor devices, it would be possible to stack such a CF film with a silicon-series insulating film like SiO2 film or silicon nitride (SiN) film and a wiring layer of aluminum (Al) or copper (Cu). However, if CF film is stacked directly on a silicon-series insulating film, for example, there is estimated the problem, due to its structure similar to Teflon (polytetrafluoroethylene), that its adhesive force to silicon-series insulating films and metals is weak and easily peels off from those materials, as well as the problem, due to weakness of silicon-series insulating films, etc. to fluorine, that surfaces of silicon-series insulating films, etc. in contact with CF films are etched and damaged. Therefore, the inventor is progressing researches about using silicon carbide films as a contact layers to enhance adhesive forces between silicon-series insulating films, etc. and CF films.
In this case, in general, a silicon carbide film can be made between a SiO2 film and a CF film by exciting deposition gas for the silicon carbide film in the above-mentioned plasma device, for example, thereby to form the silicon carbide film on the SiO2 film, and thereafter changing a deposition gas for the CF film to form the CF film on the silicon carbide film. In this connection, the inventor is continuing development of a technique for enhancing adhesion between SiO2 films, for example, and CF films.
The invention has been made under those circumstances, and its object is to provide a semiconductor device and its manufacturing method effective for making a semiconductor device using a CF film as an insulting film to enhance adhesion between the CF film and a silicon-series insulating film or between the CF film and a metal wiring layer.
To attain the object, according to the invention, there is provided a semiconductor device having a plurality of wiring layers made of a conductive material and an electrically insulating layer interposed between the wiring layers, comprising: a first insulating layer adjacent to at least one of the wiring layers and made of a fluorine-containing carbon film; a second layer located on one side of the first insulating later opposite from said at least one of the wiring layers; and a contact layer made of a compound containing silicon and interposed between the first insulating layer and the second layer to prevent separation of the first insulating layer and the second layer.
The second layer may be an insulating layer containing silicon, such as insulating layer containing silicon oxide, for example. Alternatively, the second layer may be an insulating layer containing silicon nitride or may be a metal.
The contact layer of a compound containing silicon may be one containing silicon and nitrogen, or silicon and carbon. Alternatively, the contact layer of a compound containing silicon may be one including a first compound layer containing silicon and carbon and a second compound layer containing silicon and nitrogen. In this case, the first compound layer is located nearer to the first insulating layer, and the second compound layer is located nearer to the second layer.
A third compound layer containing silicon, carbon and nitrogen may be additionally provided between the first compound layer and the second compound layer. Further, a fourth compound layer containing silicon, carbon and fluorine may be additionally provided between the first compound layer and the first insulating layer. Furthermore, a fifth compound layer containing carbon and fluorine may be additionally provided between the fourth compound layer and the first insulating layer.
According to the invention, there is provided a semiconductor device manufacturing method comprising: a first deposition step for exciting a first deposition gas into plasma in a vacuum container, and forming a contact layer on one surface of an insulating film containing silicon, or a metal film, by the plasma; a second deposition step for exciting a second deposition gas containing carbon and fluorine into plasma in said vacuum container, and forming an insulating film made of fluorine-containing carbon film on a surface of the contact layer; and a deposition gas switching step carried out between the first deposition step and the second deposition step to introduce the second deposition gas into the vacuum container while the plasma of the first deposition gas is being partially generated in the vacuum container.
According to the invention, there is provided a semiconductor device manufacturing method comprising: a first deposition step for exciting a deposition gas into plasma in a vacuum container, and forming a contact layer on one surface of an insulating film containing silicon by the plasma; a second deposition step for exciting a deposition gas containing carbon and fluorine into plasma in the vacuum container, and forming an insulating film made of fluorine-containing carbon film on a surface of the contact layer; and a third deposition step for exciting a deposition gas containing carbon and fluorine in a vacuum container different from the vacuum container, and forming an insulating film made of fluorine-containing carbon film on a surface of the fluorine-containing carbon film from the plasma.